It is sometimes required in an underground mine, to provide access from a lower level L thereof to an upper level U thereof. A mine owner may request that a raise excavation R be created from the lower level L to the upper level U, which is of a certain size/configuration and length. The raise R may be used to serve a variety of purposes such as air ventilation, secondary personnel access/egress or as material rock passes.
To create the raise excavation R, typically a pilot or access drift A is first excavated from the main mine drift D to the proposed raise location as can be seen in FIG. 1. This provides access to the raise R for both personnel and muck removal equipment (not shown). In other cases, a raise can be opened up from above in a downward direction (sometimes referred to as being ‘slashed’).
The raise climber 10 requires a drive system in order move along the rail 12 and ascend into the raise R. Traditional drive systems for raise climbers 10 are pneumatic powered (single or double), electric, or hydraulic powered motors. The pneumatic and electric powered drive systems are supplied with air or electricity by a reel of hose or cable as shown in FIG. 1. Hydraulic powered drive systems are powered by an on board diesel engine (not shown) operating a hydraulic pump.
A pneumatic powered raise climber 10 is connected to an air system in the mine via an air hose, which is towed up the raise R behind the raise climber 10. Air pressure typically fluctuates and the efficiency of the pneumatic system is directly related to the number of connections in the air delivery system. Also, the volume of air decreases as the length of hose is increased and, as such, efficiency of the drive unit decreases as the raise climber 10 ascends in the raise R. The towed hose also adds approximately 1.8 kilograms per metre to the overall load. Therefore, as the length of the raise R and the deficiencies increase, the maximum carrying capacity of the drive system becomes limited. It has been found that a pneumatic powered system can often be limited to ascending only approximately 500 metres and typically only 300 meters or less.
An electric cable drive system is also connected to an electrical system present in the mine and is attached to the raise climber 10 via an electrical cable. This adds approximately 1.5 kilograms per metre to the overall load, again limiting the carrying capacity of the drive system. It has been found that an electric cable drive system can often be limited to ascending only approximately 1500 metres.
Since both the pneumatic powered and electric cable powered drive systems are fed power from a remote location via an “umbilical” hose, there also exists the possibility of the hose being damaged or severed thus interrupting power delivery and imposing safety issues particularly in the above-described electric drive systems due to the presence of a live power cable being loose in a raise and the difficulty in repairing the cable (and loss of power) if the cable is damaged or severed.
A diesel powered drive system does not require an umbilical hose or suffer from power degradation. However, the fumes emitted by a diesel engine can be deadly, especially in a confined area and thus must be removed from the work area by pumping large amounts of air through the work area. It can be appreciated that it may be difficult to move air through the raise R as it provides a ‘dead end’ while it is being excavated and until it reaches a break through point at the upper end U. The use of diesel powered systems is consequently either banned or restricted to special circumstances by the appropriate authorities. In fact, since the early 1980s, the use of diesel units in mines in the Province of Ontario, Canada, was turned down due to fire hazard, ventilation problems and a lack of practical experience. Only for emergency purposes are diesel units therefore typically permitted.
It is therefore an object of the following to provide a power system for a raise climber that obviates or mitigates the above-noted disadvantages.